The Dynamic Relationship Between Asthma and Obesity in Schoolchildren

Yue Zhang; Zhanghua Chen; Kiros Berhane; Robert Urman; Vaia Lida Chatzi; Carrie Breton; Frank D. Gilliland

Disclosures

Am J Epidemiol. 2020;189(6):583-591. 

In This Article

Abstract and Introduction

Abstract

Asthma and obesity are among the most prevalent chronic health conditions in children. Although there has been compelling evidence of co-occurrence of asthma and obesity, it is uncertain whether asthma contributes to the development of obesity or obesity contributes to the onset of asthma or both. In this study, we used a joint transition modeling approach with cross-lagged structure to understand how asthma and obesity influence each other dynamically over time. Subjects for this study included 5,193 kindergarten and first-grade students enrolled from 13 communities in 2002–2003 in the Southern California Children's Health Study, with up to 10 years of follow-up. We found that nonobese children with diagnosed asthma at a study visit were at 37% higher odds of becoming obese by the next annual visit compared with children without asthma (odds ratio = 1.38; 95% credible interval: 1.12, 1.71). However, the presence of obesity at the current visit was not statistically significantly associated with asthma onset in the next visit (odds ratio = 1.25; 95% credible interval: 0.94, 1.62). In conclusion, childhood asthma appears to drive an increase in the onset of obesity among schoolchildren, while the onset of obesity does not necessarily imply the future onset of asthma, at least in the short term.

Introduction

Asthma and obesity are among the most common chronic health conditions in children, showing a parallel rise in prevalence over the last several decades.[1,2] In the United States, the prevalence of asthma during childhood increased from the early 1980s, and doubled from 3.6% in 1980 to 7.5% in the mid-1990s.[3] Although childhood asthma prevalence increased more slowly from 2001–2010, the latest estimates by the Centers for Disease Control and Prevention showed that asthma prevalence has increased to 8.4% and over 6 million children under age 18 have been diagnosed with asthma.[4] In the past 3 decades, the increases in obesity prevalence have been reported among all age groups in children.[5] Especially among children aged 6–11 years, the prevalence of obesity tripled from 4.2% in early 1960s to 15.3% in the late 1990s.[5] Despite previously reported declines in the prevalence of obesity among preschool-aged children (aged 2–5 years), in 2011–2014, 17% of children aged 2–19 years (about 12.7 million children) were classified as obese based on the Centers for Disease Control and Prevention criteria, with obesity prevalence being highest at ages 12–19 years (20.5%), followed by ages 6–11 years (17.5%).[6] The most recent study found that children aged 2–5 years had a significant increase in obesity prevalence since 2013–2014.[7]

A large body of evidence has shown that asthma and obesity can affect the life of children physically, emotionally, and socially.[8,9] Children with asthma often have higher risk of hospitalization and disability, and are more likely to depend on medication, have limitations in activities, and face numerous hardships in school life. Compared with normal-weight children, obese children have a higher lifetime prevalence of anxiety disorders and eating-related pathology (e.g., anorexia), and they have lower self-esteem and body satisfaction.[8] Childhood obesity has been linked with numerous adverse medical conditions, such as type 2 diabetes, sleep apnea, and cardiovascular disease. In addition, obese children are more likely to be teased or bullied, and they face a variety of hardships, including discrimination and marginalization.

Although there has been compelling evidence of co-occurrence of asthma and obesity in children,[10] it is uncertain whether one condition contributes to the onset of the other and/or vice versa. Numerous studies have shown that being obese is associated not only with increased risk of new asthma onset[11–18] but also with greater asthma severity.[19–23] In apparent contrast to these results, recent findings support an etiologic role for childhood asthma in the onset of obesity. For example, Fletcher et al.[24] found substantial long-term impacts of childhood asthma on increases in obesity. Hossain et al.[25] employed piecewise linear mixed-effect model and showed that the development of asthma in children might be associated with accelerated weight gain, which eventually leads to the onset of obesity. Chen et al.[26] found that children with asthma had higher risk of obesity. However, the limitation of the current literature is that most studies focused only on a unidirectional relationship between asthma and obesity. To our knowledge, no studies have been reported that simultaneously evaluated the potential bidirectional relationship between these 2 conditions. Green[27] explored the relationship between childhood obesity and asthma using 2 separate models; he found that onset of asthma was related to subsequent weight gain over time, but there was no association between onset of overweight and the subsequent asthma onset in separate modeling within the same study.

In this study, we used a novel dynamic joint modeling approach to examine the bidirectional relationship between asthma and obesity over time in a cohort of school-aged children who participated in the Southern California Children's Health Study (CHS). In essence, we estimated the bidirectional effects of current asthma and obesity status on the probability of becoming obese and having new-onset asthma at a subsequent annual school visit.

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